1. Field of the Disclosure
This specification relates to a log-periodic dipole array antenna for transmission and reception of wireless signals.
2. Background of the Disclosure
In general, an antenna switches an electrical signal which is represented with voltage/current and an electromagnetic wave represented with an electric field/magnetic field to each other. Types of antennas include a dipole antenna, a monopole antenna, a patch antenna, a horn antenna, a parabolic antenna, a helical antenna, a slot antenna, a log-periodic dipole array (LPDA) antenna and the like.
Here, the LPDA antenna is a type that periodically repeats the impedance and radiating characteristics for the frequency. The LPDA antenna is regarded as a frequency-independent antenna owing to insignificant variation of the characteristics over the frequency band. The LPDA is wisely used as a TV reception antenna or a communication antenna in terms of broadband characteristic and proper gain. Types of broadcast and communication services, including IMT-2000, a wireless LAN, a portable wireless Internet and the like, are much diversified in recent time. Therefore, needs of antennas which can cover a wide frequency band, a dual-band, a triple-band and the like are more increasing. This further increases utilization of the LPDA antenna.
The LPDA antennas may be classified into a sawtooth-type planar antenna, a sawtooth-type trapezoidal antenna, a trapezoidal wire antenna, a zigzag-type wire antenna and the like, according to the repetitive structure. The related art LPDA antenna has a broadband characteristic and may transmit and receive a frequency of a current antenna only when its size is about two times greater than the size of the current antenna. Also, due to the broadband characteristic of the LPDA antenna, a filter circuit has to be additionally mounted to selectively use a user-desired frequency. This causes an additional cost increase and an increase in weight and size of a system.